Along with the ever increasing integration of semiconductor devices comes a corresponding decrease in the pitch of the metal wiring used in such devices. Decreased pitch is inherent to increases in device integration. Pitch is a measured quality for describing a tightness or line-to-line proximity present in the arrangement of an array of patterned conductive lines in a semiconductor device. In semiconductor fabrication technology, pitch can be expressed in terms of aspect ratio, (i.e., the ratio of the height of a patterned structure to the width between adjacent patterned structures, which include a metal wiring layer in addition to other layers). Thus, increases in device integration naturally result in an increased aspect ratio since the minimum conductivity requirements necessitate an increase in the height of a line of metal wiring to compensate for any decrease in the line's width resulting from a reduced inter-line (inter-wire) spacing.
Meanwhile, to insulate the narrowly spaced metal lines from each other, an inter metal dielectric (IMD) material is disposed between the metal lines by forming an IMD layer on the patterned structure. However, the proper formation of such a layer becomes increasingly difficult as the aspect ratio is increased. Namely, after formation, the IMD layer often fails to completely fill the spaces existing between adjacent metal lines, thereby resulting in minute gaps (i.e., voids) occurring in corners and other recesses of at least some of the spaces. These voids can cause a variety of negative effects, including degraded device performance, reduced operational reliability, and increased defect rates.
Reference will now be made in detail to the accompanying drawings. Wherever possible, like reference numbers will be used throughout the drawings to refer to the same or similar parts.
Layer thickness, relative proportions, and other dimensions may be exaggerated in the drawings to more clearly depict semiconductor components and materials, including layers, films, plates, and other areas. Also, throughout this specification, a description of a component or material that is, for example, “formed on” an underlying component or material permits the inclusion of an interceding component or material such that the described component or material may merely be disposed at some level higher than (e.g., “above”) the underlying component or material, unless otherwise specified that there is no interceding component or material (i.e., unless specified that the described component or material is formed directly onto (e.g., “abutting”) the underlying component or material).